[Opensim-users] Urban legends (Was :Configuring a multi-hosted grid)

[Thomas Ringate]

I've been running a shared cache now for a couple of years.  I even copy 
them in a round robin fashion between my four servers so they are nearly 
identical.  I turned off the clean up so anything that has been put in them 
for about the last 10 months is still there.

As you can tell I do not have a clue how the cache is used or how it really 
works.  Since every item in is it indexed using the UUID and the first three 
digits of the UUID place them in individual folders, I have not noticed any 
folder being all that large.

The reason I do this is because three of my servers are on OSgrid, the 
fourth is where I do my scripting using two standalones which are mirror 
images of the 64 regions I host on OSgrid.  One standalone is a normal set 
of regions and the other is a single varregion.

I found I had much better success of having things appear on my standalones 
once I consolidated all of the caches, but it is still far from being 
optimal.

Now I am wondering if doing this is causing a performance hit on the three 
servers that host regions for OSgrid???
What do the experts think?

I could merge those cache into the one on the standalone server and have one 
master region clean each servers cache to some appropriate level.  I like 
the idea of a shared cache on each server.  It eliminates redundancy and 
eliminates requests by different regions for the same object.

I was surprised to hear it is not used for assets.  Why is it named 
"asset-cache"?


-----Original Message----- 
From: Justin Clark-Casey
Sent: Friday, August 22, 2014 6:54 PM
To: opensim-users at opensimulator.org
Subject: Re: [Opensim-users] Urban legends (Was :Configuring a multi-hosted 
grid)

Yeah, I've tried a shared cache before and it seems to be okay.  It's a bit 
messy because multiple simulators may
attempt to clean up the cache at the same time, which results in quite a few 
seeing messy "file not found" warnings,
though these should not be harmful.

It's hard to know how to get around this problem without making the cache 
yet another process or doing messy things like
designating only one simulator to actually clean up files.  I also think the 
cache needs a facility to limit by size
(like every other cache in the known universe :).

On 22/08/14 15:28, Jeff Kelley wrote:
> At 8:09 AM -0500 22/8/14, Marcus Llewellyn wrote:
>
> You can indeed give each instance its own asset cache directory. My 
> rationale for not doing so is that where simulators
> share content, this should reduce requests to the asset service, resulting 
> in less network traffic, and also a modest
> speed up when regions are first started in some circumstances.
>
> Because an asset may have been cached already by another simulator.
>
>
>
> My only concern has been that a single asset cache that has multiple 
> copies of Flotsam managing it might at some point
> encounter some sort of conflict or collision. So far, I've noticed nothing 
> of the sort, though. In practice, a single
> asset cache has been working fine for me.
>
> So shared cache is a better option, until we discover a drawback.
>
>
>
> -- Jeff
>
>
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>


-- 
Justin Clark-Casey (justincc)
OSVW Consulting
http://justincc.org
http://twitter.com/justincc
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